Project Summary/Abstract The goals of this fellowship are to further develop the applicant?s knowledge and research skills in anxiety and comorbid disorders, advanced statistical methods (particularly longitudinal methods), and psychophysiology. In line with these goals, the cornerstone of the applicant?s training will be the daily activities associated with the proposed study of the directional relationships between anxiety and cannabis use (i.e., whether anxiety is associated with subsequent cannabis use and/or whether cannabis use is associated with subsequent anxiety) and whether sensitivity to unpredictable threat (SUT) moderates these directional relationships. The project will serve as the applicant?s dissertation and help her pursue her goal of becoming an independent investigator who utilizes psychophysiological techniques to further our understanding of how transdiagnostic constructs, including SUT (one of the main constructs examined in this diversity NRSA application), contribute to vulnerability for anxiety disorders (ADs) and co-occurring psychopathologies. The proposed training plan is multidimensional and includes course work, regular sponsor meetings, statistical training, and professional development activities. In addition to the skills to be gained by the applicant, the project?s goal is consistent with several facets of NIMH?s strategic plans as it has the potential to greatly advance understanding of the processes contributing to why ADs frequently co-occur with cannabis use disorders (CUDs). It is critical to understand the comorbidity between ADs and CUDs as this comorbidity is associated with costly social and economic consequences and rates of CUDs may further increase due to recent changes in social acceptability and state cannabis laws. Ecological momentary assessment (EMA) is a method that can help elucidate the temporal relationship between anxiety and cannabis use as it captures subtle variations in mood and behavior as they occur. The handful of EMA studies on anxiety and cannabis use have been mixed, however, and had several important limitations. Moreover, there are likely specific individual difference factors that impact the association between anxiety and cannabis use. Heightened sensitivity to unpredictable threat (SUT) is one such individual difference factor as it connotes vulnerability for ADs and is also likely to play a role in cannabis use. The present study will therefore utilize a multimethod assessment of SUT (e.g., EMG startle, event-related potentials, and self-report) to test (1) the directional relationship between cannabis use and anxiety (and state experiences of SUT more specifically) and (2) whether trait SUT moderates the temporal relationships between state anxiety (and state SUT) and cannabis use in 60 moderate cannabis users over a 2-week EMA period. Mentorship for this project will be provided by experts in the areas of psychopathology, substance use, EMA, and psychophysiology (sponsors: Shankman and Mermelstein, and collaborator: Childs). This fellowship will not only be an important step in the applicant?s research career, but if the hypotheses are supported, it would help guide the development of novel interventions targeting unique biologic vulnerability processes related to this difficult-to-treat population.